May 2016

Event Date: 
Tuesday, May 31, 2016 - 18:00 - 18:15
Institution: 
TBA
Title: 

Ecology and functional analysis of microbial communities in phytoremediation and grapevine endosphere

Abstract: 

The biosphere is dominated by microorganisms and contains about 6×1030 prokaryotic cells. This number represents at least two to three orders of magnitude more than all of the plant and animal cells combined. Microorganisms are highly diverse group of organisms and constitute about 60% of the Earth’s biomass. Microorganisms are key players in important ecological processes such as soil structure formation, decomposition of organic matter and xenobiotics, recycling of essential elements and nutrients, suppressing soil-borne plant diseases and promoting plant growth. An understanding of microbial dynamics and their interactions with biotic and abiotic factors is indispensable in bioremediation techniques, and in biotechnological industries such as pharmaceuticals, food, chemical, and agriculture. 
This talk consists of two parts. Fist part is about plant-microbe interactions in phytoremediation of organic and inorganic pollutants. Organic and inorganic pollutants discharged due to accidental or anthropogenic activities, into the environment pose global peril, as they not only ominously threaten human wellbeing, but also have noxious effects on the whole ecosystem. Phytoremediation is highly versatile, solar-driven in situ pollutant extraction system for removal of ecosystem trembling contaminants from soil, water, sediments and air. In phytoremediation plants and their associated microbes work in symbiotic relationship. Different phytoremediation projects were successfully completed for the removal of contaminants. Cultivation-based as well as cultivation-independent analysis techniques were used to study microbial ecology, diversity, colonization and degradation potential. These studies suggested that the application of microbial strains, which are able to compete with the native microflora and to tightly associate with plants, are promising candidates to be used for phytoremediation applications. 
Second part deals with microbial endophytic communities associated with grapevine and functional analysis of their interaction with plants. Endophytes, as host-associated microbes, respond to environmental stimuli in a host-mediated fashion. To study how temperature, climate, cultivars and agronomic practices may affect endophytic microbial communities, we studied grapevine-associated microbial populations using a cultivation-independent approach. The plants were sacrificed at sampling; DNA was extracted from roots and stems after surface sterilization and abrasion. Total DNA was extracted and bacterial 16S was PCR amplified and purified. Multiple reactions were pyrosequenced at once using Roche 454 GS FLX+ Titanium technology, using Multiplex Identifiers during PCR. We adopted a DNA-based approach to the analysis of microbial populations’ variation as a response to environmental conditions. Grapevine stems and roots showed complex, rich and distinct endophytic communities. We could clearly identify an intuitive pattern of changes in endophytic microbial composition across temperatures, cultivars and agronomic practices.

Event Date: 
Tuesday, May 31, 2016 - 18:15 - 18:30
Institution: 
UTS
Title: 

Single cell measurements of metabolic activity using isotope-labelling techniques and Secondary Ion Mass Spectrometry

Abstract: 

The metabolic activities of microbial cells drive biogeochemical cycles, and drastically influence the productivity and the functioning of all ecosystems. Until recently, the metabolic activities of microbial communities have been investigated using traditional approaches, requiring large sample amounts collected over wide spatial scales. These approaches are fundamentally disconnected from the micrometer-scales over which microbial cells interact with sources of nutrients. 
In this talk, I will present recent development in combining isotope-labelling techniques with Secondary Ion Mass Spectrometry (SIMS) analysis in order to monitor metabolic activities of uncultured microbes at the single-cell level. This includes high resolution imaging using NanoSIMS but also the Time Of Flight Secondary Ion Mass Spectrometer (TOF-SIMS) facility recently installed at the University of New South Wales. The methods and preliminary results are of great potential to explore how the metabolic activities of microbial communities vary across space and time.

Event Date: 
Tuesday, May 31, 2016 - 19:00 - 19:45
Institution: 
UNSW
Title: 

Scientists Seeing Red: Neutral Red Crystals rewire energy towards a burst in methane

Abstract: 

Biologically produced combustible gas (biogas) has a large role to play in Australia’s future energy security. Australian coal deposits have a large potential for methane generation via microbial biogasification. In our project we enhanced microbial methane formation from coal-associated ground waters through the application of the synthetic phenazine neutral red. The amendment was conducted in 80 m deep wells penetrating a coal seam in Australia and performed in triplicate. The synthetic phenazine neutral red (2-amino-8dimethylamino-3-methylphenazine) is a redox active dye shown to stimulate methane production in bioelectrochemical systems. Recently, we discovered that 250-500 μM neutral red substantially increases methane production from anaerobic coal-fed cultures through the formation of self-assembling neutral-red needle like structures. Our studies proved that these flexible neutral red structures are crystalline with a length of 100-1500 μm and a width of 1-5 μm. Furthermore, we showed that they act as organic semiconductors mediating the electron transfer and enhancing the conversion of carbonaceous material to methane by rewiring the electron flow in favor of biogas producing microbial communities. In vitro membrane test showed that reduced neutral red donates electrons into the respiratory chain of Methanosarcina mazei. In situ methanogenesis outperformed other enhancement methods shown in the past as well as the stimulation of biomass production of methanogenic archaea. Furthermore, bacterial representatives of the coal-associated groundwater community related to Rhizobium, Shewanella, Hydrogenophaga, Clostridium, Geosporobacter, and Geobacter species were stimulated whilst the growth of sulfate-reducing bacteria was inhibited favoring methane production.